/*
 Copyright (c) 2022, Apple Inc. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,
 are permitted provided that the following conditions are met:
 
 1.  Redistributions of source code must retain the above copyright notice, this
 list of conditions and the following disclaimer.
 
 2.  Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation and/or
 other materials provided with the distribution.
 
 3. Neither the name of the copyright holder(s) nor the names of any contributors
 may be used to endorse or promote products derived from this software without
 specific prior written permission. No license is granted to the trademarks of
 the copyright holders even if such marks are included in this software.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import Foundation

extension OCKReadOnlyEventStore {

    /// Join partial event data and outcomes into events, matching on the task UUID and occurrence index.
    /// It's safe to call this method with outcomes that don't match any of the partial events.
    func join<Task: OCKAnyTask, Outcome: OCKAnyOutcome>(
        partialEvents: [PartialEvent<Task>],
        outcomes: [Outcome]
    ) -> [OCKEvent<Task, Outcome>] {

        // Group outcomes by task UUID for quick lookup later on
        let outcomesGroupedByTaskUUID = Dictionary(grouping: outcomes, by: \.taskUUID)

        // Convert partial events to full fledged events. We will fill in the
        // outcomes later
        var events = partialEvents.map {
            OCKEvent<Task, Outcome>(task: $0.task, outcome: nil, scheduleEvent: $0.scheduleEvent)
        }

        // Fill in the outcomes for each event by matching the task UUID and occurrence index. It's important to
        // iterate through events and return them in the same order to help maintain the existing sort order.
        for i in 0..<events.count {

            let event = events[i]
            let uuid = event.task.uuid

            let outcome = outcomesGroupedByTaskUUID[uuid]?
                .first { $0.taskOccurrenceIndex == event.scheduleEvent.occurrence }

            events[i].outcome = outcome
        }

        return events
    }
}
